1. Field of the Invention
This invention concerns fluorescent monoazo paper dyes, green-yellow to orange in color, containing therein barbituric acid unit(s) or a derivative thereof.
2. Description of the Prior Art
U.S. Pat. No. 3,426,010 discloses yellow monoazo paper dyes wherein the coupling components are 3-alkyl-5-pyrazolones which are nonanalogous to the barbituric acid and derivative that are coupling components herein. Further differences between the reference dyes and those of this invention are that the reference dyes are not fluorescent and they are surface active. The dyes taught herein are fluorescent, and they are not surface active. Furthermore, the reference is silent concerning a fluorescent green-yellow dye that produces a bright green shade on paper when mixed with a blue dye.
U.S. Pat. No. 2,686,178 discloses disulfonated disazo dyes that gives violet-brown color shades. The dye molecule is significantly more complex than that of this invention, having a ##STR2## moiety which forms no part of the present invention.